Answer:
1. synthesis reaction
2. Double displacement reaction
3. Single displacement reaction
4. decomposition reaction
Step-by-step explanation:
1. The atoms combine together, thus it's synthesis.
2. The Ca bonds to NO3, whereas the Ag bonds with Cl2.
3. The Zn bonds with SO4 from CuSO4, but the Cu is removed from the initial bond.
4. The initial reaction, 2Na2O, breaks down (decomposes) into two separate atoms.